Hybridoma-derived monoclonal antibodies targeting a viscumin epitope: a novel approach for detection and potential therapeutic applications.

Mistletoe extracts contain the ribosome inactivating protein viscumin, which exhibits effectiveness in alternative therapies but also presents considerable toxicity risks. Hence, specific and sensitive diagnostics for identifying viscumin exposure should be developed. This study aimed to develop monoclonal antibodies (mAbs) to viscumin and to test their protective capacity against its cytotoxic effects. A peptide epitope, representing A-chain of viscumin of 9 amino acids, was synthesized and conjugated to Bovine Serum Albumin (BSA) for the immunization of BALB/c mice. Spleen cells from immunized mice were fused with SP2/0 myeloma cells to obtain hybridomas. The generated mAbs for viscumin were selected through ELISA and further characterized. The cytotoxicity of mistletoe extract against Hep-G2 cells was conducted with the SRB assay, which revealed a reduction in cell viability, respectively: about 80% at 2.5 μg/mL, 64% at 5 μg/mL, and 46% at 10 μg/mL. Interestingly, it was observed that the mAbs significantly mitigated the cytotoxic activity of viscumin, causing the viability of about 86% at all tested concentrations. Hence, they showed potential for mAbs in developing sensitive diagnostic assays and therapeutic strategies to counteract the toxic effects of viscumin. Further mAb variants' characterization, epitope mapping, and determination of the affinity should be conducted to improve both diagnostic and therapeutic avenues of viscumin-induced toxicity.